Outer Limits 4x4 Board

O' righty, here we go.
I have the infamous RD28T under the bonnet of my MQ/MK (whatever the leafsprung W260 was called outside Europe) and in october last year the head gasket let go at 250k kms. I pulled the head, just to see cracks everywhere and got a remanufactured one. So far, so good. A few weeks later I noticed that the Patrol was hard to start in the mornings and smoked like crazy. I checked the glow plugs and the ones for cyl. 4-6 were burned. I ordered new ones and for sure they've been on backorder until mid-january so I had to do my Sahara trip with only 3 plugs working. Since it was winter time here in Germany and in the Sahara we had freezing temps and my battery nearly died on me. Anyway, eventually I got the new plugs, put them in, fine. For two weeks. I start and nothing. So I pulled the plugs again and one was totally melted and made a short, killing again # 4-6 and the relais. So I had them replaced under warranty, which took anozher six weeks, put the new ones in and....... you guess it, they lasted two weeks. Smokes came frome under the bonnet and the wires burned including the brand new 70$ relais. For now I use a chemical starter spray which I doubt is good for my engine. What can be wrong ? I dunno where to start anymore
It's a shame that we never got the TD42's over here. Only a few have been imported privately

Sounds like you have a short at the connection to the glow plugs.

you using the right glow plugs?? meaning...24v in a 24v system?? dumb questions I know but...seems like 12v stuff in 24v system wuld burn up like this. My 83 is imported from Germany and it is all 24 volt with the glow plugs and headlights converted to 12v. It doesn't burn anything but is a crappy set up and I will go back to full 24v.

RMP&O wrote:you using the right glow plugs?? meaning...24v in a 24v system?? dumb questions I know but...seems like 12v stuff in 24v system wuld burn up like this. My 83 is imported from Germany and it is all 24 volt with the glow plugs and headlights converted to 12v. It doesn't burn anything but is a crappy set up and I will go back to full 24v.

What i was thinking as well...

12 or 24 volt system??

TOM

RMP&O wrote:you using the right glow plugs?? meaning...24v in a 24v system?? dumb questions I know but...seems like 12v stuff in 24v system wuld burn up like this. My 83 is imported from Germany and it is all 24 volt with the glow plugs and headlights converted to 12v. It doesn't burn anything but is a crappy set up and I will go back to full 24v.

I thought you could not import any vehicle under 25 years old into the sates?

I thought you could not import any vehicle under 25 years old into the sates?

this is way off that guys topic...but yea that is right. My MQ came in back in 1988. Imported by the original German owners....I assume it was done before laws changed. It is a very rare truck in the USA because of this....

The RD28's are all 12 Volts over here and the plugs are the correct one, we checked it a couple of times. A short in the circuit to the plugs and the connection is also checked and everything is fine there.
@RMP&O
You should kow me as BART in some US forums

@RMP&O
You should kow me as BART in some US forums

Ah-ha!

Well WTF man!? Is it set up with an auto timer on the glow plugs? Meaning the key runs them and they shut off on their own at spefic time? If so maybe the probelm is in here somewhere....such as running them much to long or supplying way to much juice? Spent any time on it with a test light under various conditions? Mine are converted to a push button and works just great other than they are 12v on a 24v system with little converter pods.

I am not really sure what it could be, only poked around with my wiring a bit and it is an SD33. Some of these guys should have some better suggestions.

I have to wonder about your water problem,is it all fixed or is there still a pressurization or water loss problem.I can not see an external wiring fault melting glow-plugs unless they are staying on. If it was a spark plug melting I would say lean mixture or water {steam} in the combustion chamber, especially so many times on the same cylinders.
J Top

The water problem is definitly solved with a remanufactured head and no water loss at all. The timing is controlled electronically with an ECU. I'll give them one more try with OEM Nissan plugs and see what happens. The ones that melted were aftermarket (Nipparts) parts. I just got off the phone with a friend who has converted his 260 from the RD28T to a SD33T which is quite a work including adapters for the rear driveshaft and using the rear axle of the 3.3 because of the off-center diff. The wheelbase is also different (~ 2 1/4" longer on the 260) and the motor mopunts have to be fabricated as well as a new crossmember.

if the motor is a 2.8 turbo diesel i have heard that they use two different type of glow plugs on the motor....just a vague memory but worth checking out as if you fit them in the wrong position..........

big red wrote:if the motor is a 2.8 turbo diesel i have heard that they use two different type of glow plugs on the motor....just a vague memory but worth checking out as if you fit them in the wrong position..........

They indeed have two different kinds of glow plugs in there. Cyl. 1-3 with short thread on top and 4-6 with the long thread. It's impossible to mix them up, they just won't fit, but was worth the idea.
I'm already considering swapping the 2.8 against a 3.3T, but this would include a lot of work on the frame too

well...if you are going to do that Bart why not drop a 6.2L or 6.5L GM diesel in there?? I think Dellow has kits...

RMP&O wrote:well...if you are going to do that Bart why not drop a 6.2L or 6.5L GM diesel in there?? I think Dellow has kits...

Problem with that is, I don't get it street legal here. I can easily fit the 3.3 because it was a factory option here but not the 6.5 (which would be a dream )
I may look for one of the very rare TD42 GQ's here. Most of them (there are around 25 !! in Germany only) are ex-UN from ex-Yugoslavia.

The glow plug control system for the 2.8 has 2 operating modes. 1 mode where all glow plugs are switched on with full battery current and a second mode where the plugs operate with reduced current (presumably to prevent them burning out). In this second mode, the plugs continue to operate until the engine is up to a suitable operating temperature after which they are turned off. I cant remember IF in this second mode, it turns on all the plugs or only 4,5 & 6


Might be worth checking if the controller is working properly before you replace any more plugs--check all the inputs from the various sensors..

Nick

Also from looking at the circuit diagram for the glow plugs, it looks like if both relays were to switch on (which they are not supposed to according to the description of how the system works) a short circuit would occur and the current created would either blow a fusable link,melt the cabling, or be dissipated by the glow plugs........ Check that only one relay is energising at once...

It appears that when the second relay is NOT energised , it supplies the earth return for 3 of the plugs(the other 3 earth internally). When this second relay turns on, it then supplies battery power to the plugs. A short circuit is avoided, as the first relay is now turned off by the controller...... SO maybe this is the fault......??

Hope this makes sense???

Nick

So, after some thinking and wrenching I had the new plugs out of the engine gain and tested them. I supplied power to each plug and the 3 shorter ones (cyl. 1-3) worked fine, #4 also glowed, #'s 5&6 were dead. Interesting enough, as soon as #4 which is one of the longer ones heated up it created a short circuit causing the wires and the relay to burn. So for now I put an additional shorter one in there instead of #4 and let the #5&6 as they were. Problem then was that the ECU discovered some strange electrical data and stopped the pre-glow process and I had no power at the plugs. The solution for now is a manual push-button in the dash to give power to the relay and have all 6 plugs powered at the same time for about 10 seconds. With only 4 of them working it starts like a charm even at nearly freezing temps we had last night. It really seems that the aftermarket plugs caused all this trouble, so I'd really stay away from Nipparts from now and get 2 new short NGK plugs for #5&6 and have a time relay giving them 10 seconds power at each start, maybe with an additional temp sensor. For now and forever the stock ECU is disconnected and will stay out of business.

what are they worth in the states, new and secondhand?????

RMP&O wrote:well...if you are going to do that Bart why not drop a 6.2L or 6.5L GM diesel in there?? I think Dellow has kits...

[size=18]Dont forget that 3 of the glow plugs are dfferent from the other 3. One type of glow plug earths via the thread that you screw it into the cylinder head with, while the other type has a cable that runs back to earth via one of the relays. Mixing them up would not be a good idea!


Try using a high wattage 12v lamp as a load instead of the glow plugs to trace the fault with the system. Its far cheaper to replace than the glow plugs or relays.
Remember also,that when testing the glow plugs( when not installed in the engine), and with the type that earths via its screw-in-thread, you'll need to use a jumper lead or similar to create a ground so it actually works. The other type, you need to earth them also with a cable but this will connect to the lower portion of the top connection thread.

Good luck!